As a student, I would like to interject here with a couple of comments
and questions...

1. I have learned from this discussion that everyone has an opinion,
and their opinion is quite strongly held. Does anyone have any data,
on either side, to back up their opinion? How often do planes have
trouble caused by not knowing precisely how much gas they have,
perhaps influenced by inaccurate gages? How often do planes have
trouble caused by running a tank dry (NOT running the _last_ tank
dry)?

2. There seems to be a lot of discussion mentioning that the only way
to be sure of your tank's capacity is to run it dry. In my reading
about flying, I notice that folks talk about measuring fuel by looking
in the tanks and perhaps using a dipstick. Couldn't you calibrate
your gages by filling the tanks, going for a flight, then sticking a
ruler into the tank to see how much is left? Is running the tank dry
any more accurate or useful?


To me, the two sides of this debate seems to be as follows: some folks
want to be in control of every aspect of their flight, while other
folks want to have as wide of a saftey margin as possible at all
times. The fuel tank issue is one where these two goals conflict.

To the control oriented folks, having a tank run dry when they expect
it gives them one more data point which makes them more comfortable
and feel more in control during the flight. Any small change in
flight characteristics is detectable by a change in tank switch
timings, and so these folks are willing to accept what they think is a
small risk in changing tanks in order to detect any problems.

The safety margin folks feel more comfortable not knowing precisely
how much margin of safety they have, as long as that margin is wide
enough that they never have to worry about it. To these folks minor
problems will be covered by their ample margin of safety, and major
problems will become apparent on their gages. These folks want to
make sure they have as much fuel as possible in reserve in all tanks
when the major problem hits, and don't worry about missing a couple of
minor problems as a result.

Is my characterization accurate?

Chris
--
Chris Colohan Email: PGP: finger
Web: www.colohan.com Phone: (412)268-4751